1) the ground (middle wire on a 3 pin Bosch style connector) that gives continuity between it and the metal chassis/body

2) The +5V reference wire (using a multimeter i get 5V on one of the outer pins when grounded to body.

3) therefore the other wire on the harness is the signal.

my issue is that once i connect the sensor into the harness i no longer get the 5V reference between the 5V wire and ground it drops to 1.6V.

if i remove the sensor ground wire from the harness leaving only the 5V and signal wire from the sensor plugged into the harness i do get 5V its just when i put the sensor ground wire into the harness i dont get the 5V ref

basically i cant get any sort of signal out of it.

yet when i connect it to a 12V battery to bench test off the car it seems to produce the expected signal.

i am able to get a different brand TPS to work properly so the harness doesnt seem to have anything majorly wrong

Also, you should be sure you understand the wiring on your harness. Can you back-probe the connector with known good sensor attached and verify the signals?_________________------
ferg@veracitydata.com
Veracity Racing Data
http://veracitydata.com

Also, you should be sure you understand the wiring on your harness. Can you back-probe the connector with known good sensor attached and verify the signals?

the wires on sensor i know are correct, they are reasonably clear, i have seen the specs, and i have bench tested it and it works fine. i have also had a couple other different brand sensors bosch, wabash etc working but they are the resistive track type

perhaps there is a resistor in the harness wiring so the contactless inductive signal gets screwed up? electrical theory is not my strength

in the specs it says

"Load resistance 10KΩ minimum (resistive to GND) " im not sure how to check this or what it really means

After re-reading the data sheet it's not talking about a pull up resistor as I thought. As you say it talks about the minimum "load resistance" All can think of if you disconnect the cars battery and put a multimeter across the signal to the ecu and ground to measure what resistance you have.
Would it be worth tracing the wires back to the ecu just to make sure nothing has been wired in ie resistors? as it's strange that the supply voltage drops to 1.6 volts with the Hall Effect on in place. Is the ecu capable of supplying enough current to power it? although the sheet does say <25ma.

You haven't identified any wire colors or positions, sounds like it isn't wired correctly. Some ECU's put a 5v bias on outputs, just because it has 5v doesn't mean its the 5v supply. Don't assume anything, VERIFY vehicle wiring before going further.

You haven't identified any wire colors or positions, sounds like it isn't wired correctly. Some ECU's put a 5v bias on outputs, just because it has 5v doesn't mean its the 5v supply. Don't assume anything, VERIFY vehicle wiring before going further.

purple was 5v
brown was GND
green signal

i know the wiring on the harness because ive just connected up a different sensor until i can sort the issue. also i did check the various combinations incase but basically i get zero output no matter what i did

So i added a 5K resistor to ground on my simple bench test setup that uses a 6V battery and it seems like i am able to reproduce a similar effect that i am seeing on the car plugging into the actual harness.

am i right in saying this seems to suggest there is a pull down resistor somewhere in the system that needs to be removed?

Common TPS wiring for many jap cars, eg Mitsubishi, there's a 5v power feed to it, ground at the other end, the signal varies between the two depending on position.
Output is 0v to 5v depending on position.

By "load" they mean the input resistance of the ECU which the signal is feeding.

Common TPS wiring for many jap cars, eg Mitsubishi, there's a 5v power feed to it, ground at the other end, the signal varies between the two depending on position.
Output is 0v to 5v depending on position.

By "load" they mean the input resistance of the ECU which the signal is feeding.

Also, you should be sure you understand the wiring on your harness. Can you back-probe the connector with known good sensor attached and verify the signals?

the wires on sensor i know are correct, they are reasonably clear, i have seen the specs, and i have bench tested it and it works fine. i have also had a couple other different brand sensors bosch, wabash etc working but they are the resistive track type

perhaps there is a resistor in the harness wiring so the contactless inductive signal gets screwed up? electrical theory is not my strength

in the specs it says

"Load resistance 10KΩ minimum (resistive to GND) " im not sure how to check this or what it really means

You guys have to get down to ohms law and basic electrical diagnostics here- there are only 3 possibilities for this voltage drop - and one of them you tested for when you unplugged the signal wire and tested it with your multi meter. So first take your multi meter on resistance scale, unplug the sensor and measure the resistance across the 5 volt lead and the ground lead. From what you posted above sounds like you should read close to 10k ohms there. If you read much less than this then get a new sensor- if you do read 9k-10k ohms then you must have a pathetic 5 volt ref signal that shows 5 volts on your very high impedance multi meter but doesn't have enough current to maintain 5 volts across a 10k ohm resistor. In that case try the test again with a clean 5v ref straight out of the ecu.

The issue is definitely 5V ref, the P&G sensor works fine and outputs correctly on a different car where the 5V ref is maintained at 5V with sensor connected.

Even on a regular resistance pot type BMW OEM TPS sensor the 5V ref is dropping to 2.3V or so with the sensor plugged in and hence the open and closed voltages don?t offer a good resolution for tuning, yet it still functions in a ?useable? manner .

I have temporarily abandoned trying to get the P&G sensor working and trying to sort the root cause being the 5V supply. I guess as said I should check 5V at the ECU side with the sensor connected.

One chap I spoke with suggested I should get an alternative 5V source besides the ECU and feed the signal back to the ECU but I will prefer to go forth the most logical path first which is investigate why the ECU doesn?t operate as expected.